how NOT to clean ancient coins

[Jon the Lecturer]

Hi everyone,

About a year ago I cleaned my coins very ignorantly and in the wrongest possibly way. Since  I used to be a goldsmith I used jewellery method which employs annealing the coins and then throwing the extreme hot coins in hydrocholoric acid.

The result is in the pictures . I wonder though If I ruined any good coins or I mean did I really ruin them ?

Anyway, I think noone should heat coins and throw them into acid Smiley It is just ignorant Smiley

Regards

Jon

PS: disregard the two uncleaned coins in the picture, I just happened to scanned them together

So, you should never heat the coins ad throw in the any kind of acid, that would ruin the patina for good. 

this topic was posted at another part of the forum :

https://www.forumancientcoins.com/board/index.php?topic=56530.0;topicseen

[Salem Alshdaifat]

DONT feel bad at all, I ruined thousands in coins befor I learn, and I think I learned the best I can   , but I think you went realy Wild 
regards
Salem

[areich]

Don't worry, what's a few thousand coins, there are more where those came from. 

[Danny S. Jones]

Salem,

I've got to know. How did you ruin thousands of coins      
What in the world were you doing?

 

[Salem Alshdaifat]

I will give one example .
when I first start buying bronze coins I used to over clean them till they are shiny , and was thinking it is better, I cleaned thousands of them like this and when I start to see the internet when it first came to my place, I found that I was stripping coins and not cleaning them.

one time by mistake I ruined around 3000 Constantinian coins but by mistake, I added a strong Acid that I use for cleaning silver coins instead of light Acid, when I saw the smoke I relaize some thing was wrong, I looked at the Acid container and found out what was wrong 
the whole hoard went to my junk box.
regards
Salem

[Danny S. Jones]

Wow... I don't feel so bad anymore about the coins I've ruined. Smoke emanating from a coin can never be a good thing. Well, you've definitely made up for it with Holyland. Wish I could afford to ruin 3000 coins.... not that I want to ruin 3000 coins. Oh well, I've ruined my fair share, so I won't get to jealous.

Danny

[areich]

I'd rather no one ruined thousands of coins by taking off their patina with acid. 

[Salem Alshdaifat]

light Acid with green water hoard deposit wont take the patina if the coins are silvered, if you use the right Acid it will take the green dirt and leave the original Patina and silvering intact.

Salem

[Jon the Lecturer]

Well,

I do not feel as bad anymore,  I only ruined o let's say remove the patina and roughness of about 9 coins , not thousands ...
This is a lesson for al, especially for novice collectors .

best

Jon

[Heliodromus]

light Acid with green water hoard deposit wont take the patina if the coins are silvered, if you use the right Acid it will take the green dirt and leave the original Patina and silvering intact.

Salem

Salem,
Is it the type of acid that matters (for cleaning bronzes), or just the concentration? Any hints would be appreciated!

Ben

[gavignano]

Just a note to more recent Forvm members - for quite a while now Salem has been sharing some of his experiences, including dropping hints about a particular technique he notes he paid tens of thousands of dollars to know. I will admit some of the pictures he has posted are astonishing (how nicely they cleaned). I will say to any novice though, acids should only be used by the highly knowledgeable in a well ventilated area - its not even close to a safe substance.
Salem has noted he does his work outside.

[Ed Bear]

Salem,
Is it the type of acid that matters (for cleaning bronzes), or just the concentration? Any hints would be appreciated!
Ben

 I've been doing a bit reading in metallurgy lately and I'm almost ready to start a few experiments, but I'm also starting to see why people might be hesitant to communicate things casually.  The behavior of some acids on copper alloys can vary quite a bit depending upon conditions, but giving people recipes for this kind of thing could also lead to disaster! 

[Paul D3]

I would not use any but an extreamly weak acid solution such as olive oil unless you are going to sit and watch the acid work-not place on a shelf and check back ina day or two.
I assume that ancient bronze coins have certain "Impurities" such as traces of silver or other metals, and there is no consistacy in what impurities or which impuritues are present in any given coin.
For instance, ancient coin bronze should just be copper with some tin. An acid that goes easy on those may attack an impurity that whose presence  in unknown to the cleaner, resuting in a rough, pitted coin

[Robert_Brenchley]

I've used white vinegar successfully, in short soaks alternating with brushing, to get rid of a mass of green across the surface of a Postumus bronze. The coin had already lost any patina it had ever had in previous attempts at cleaning, and the vinegar did no further harm. I'd hesitate to use it on any coin with patina though.